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Objective:To synthesize Gd labeled probe targeting transporter protein(TSPO) 2-(8-amino-2-(4-chlorophenyl)imidazo[1, 2-a]pyridine-3-yl)- N, N-dipropylacetamide (CB86)-diethylene triamine pentaacetic acid (DTPA), and investigate its MRI effect in rheumatoid arthritis (RA) model. Methods:CB86-DTPA was prepared by coupling a bifunctional chelating agent, and then chelated with Gd to obtain MRI targeted contrast agent CB86-DTPA-Gd. The cytotoxicity, MR relaxation rate and in vitro stability of CB86-DTPA-Gd were determined. RA model was established with Freund′s adjuvant and the biodistribution study and MRI was performed. The RA lesion and its surrounding normal tissue were used as regions of interest (ROI) to calculate the signal to noise ratio (SNR). Independent-sample t test was used to analyze the data. Results:CB86-DTPA-Gd had excellent biosafety and a good MR relaxation rate ( r1=11.05 mmol·L -1·s -1). The survival rate of RAW264.7 cells and 4T1 cells was still more than 90% at the maximum concentration (20 μmol/L) of Gd 3+. CB86-DTPA-Gd also exhibited good stability in human serum and phosphate buffer saline solution (PBS; pH=7.4). The in vivo biodistribution showed that CB86-DTPA-Gd had better inflammatory targeting efficiency, and the uptake of Gd in the inflamed site of the ankle joint was still (2.33±0.29) percent dose rate per gram of tissue (%ID/g) at 120 min after injection. MicroMRI showed that the inflammation of the right ankle joint displayed significant enhancement after the injection of CB86-DTPA-Gd and Gd-DTPA. The SNR of CB86-DTPA-Gd group was up to 23.21±1.44, and the maximum intensification time was 90 min after injection, and can be significantly inhibited by CB86-DTPA at all time points ( t values: 6.083-12.451, all P<0.05), while the Gd-DTPA group had a strengthening time of 30 min after injection with the SNR of 16.12±1.24. Conclusion:CB86-DTPA-Gd shows good macrophage targeting and good uptake in arthritic reaction sites, and is expected to be a novel MRI molecular probe for peripheral inflammation imaging.
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Objective To synthesize a novel 18 F labeled probe targeting translocator protein ( TSPO) ligand 2-( 5, 7-diethyl-2-( 4-( 2-fluoroethoxy ) phenyl ) pyrazolo [ 1, 5-a ] pyrimidin-3-yl )-N, N-diethylacet-amide (VUIIS1008), and evaluate its biodistribution and imaging in rheumatoid arthritis (RA) model. Methods The tosylate substrate was labeled with 18 F using a tosyloxy for fluorine nucleophilic aliphatic substitution to obtain 18 F-VUIIS1008. The labeling efficiency, radiochemical purity, and stability in vitro were determined. In vitro cellular uptake and competitive binding assay were performed on RAW264.7 mac-rophage cells. Biodistribution and microPET/CT imaging were investigated on RA mice established by Com-plete Freund's Adjuvant. Two-sample t test was used to analyze the data. Results 18 F-VUIIS1008 was syn-thesized with the labeling yield up to (41.00±5.00)％, the radiochemical purity>98.00％, and the specific radioactivity >1. 52 × 108 MBq/mmol. 18 F-VUIIS1008 was highly stable with the radiochemical purity >98. 00％ at 4 h after incubation in mouse serum. In vitro, it also exhibited high specific TSPO binding in RAW264.7 macrophage cells. The uptake ratio was (14.00±0.30)％ at 1 h after incubation, and decreased significantly ((4.00±0.70)％;t=12.894, P<0.05) after adding excessive unlabeled VUIIS1008. The half maximal inhibitory concentration (IC50) of 18F-VUIIS1008 binding to TSPO was 0.05 nmol/L in RAW264.7 macrophage cells. In vivo distribution results showed that the uptake of 18 F-VUIIS1008 in the left arthritic ankles reached the peak value of (1.33±0.02) percentage activity of injection dose per gram of tissue (％ID/g) at 1 h after injection. The radioactivity ratio of left ankle arthritic tissue to blood ( A/B) and to normal muscle ( A/M) was 4.40±0.22 and 1.65±0.07 respectively. MicroPET/CT imaging demonstrated that 18F-VUIIS1008 could specifically target and retained in the inflammation site. Conclusion 18 F-VUIIS1008 can be easily synthe-sized with high radiochemical purity and can clearly visualized in RA imaging with low background, suggesting its potential as a novel promising molecular probe targeting TSPO for RA PET imaging.
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Objective To prepare 131I-anti-neuropilin-2-monoclonal antibody (131I-anti-NRP-2-mAb),and investigate its biodistribution and imaging in nude mice bearing xenografted lung adenocarcinoma,in order to evaluate its feasibility as an imaging agent targeting to NRP-2 positive tumors.Methods (1)131I-anti-NRP-2-mAb was prepared by Chloramine-T method under the optimum labeling conditions,then the labeling efficiency,radiochemical purity and stability were determined in vitro.(2) The binding fraction and receptor binding affinity of 131I-anti-NRP-2-mAb were measured in A549 human lung cancer cells by cell uptaking and binding experiments.(3) The A549 tumor-bearing mice were randomly divided into 4 groups with direct sampling method and were sacrificed at 6,24,48,and 72 h,respectively,after tail intravenous injection of 0.37 MBq 131I-anti-NRP-2-mAb.The distribution was measured,and the ratios of tumor/muscle (T/M) and tumor/blood (T/B) were calculated.(4) Gamma imaging was performed in 6 mice,including 3 in the competitive inhibition control group (injected with 3.7 MBq 131I-anti-NRP-2-mAb and 100 μg atniNRP-2-mAb),at 6,24,48,and 72 h post-injection to observe the radioactivity in tumor.Two-sample t test was used for data analysis.Results (1) The labeling yield and radiochemical purity of 131I-anti-NRP-2-mAb were (94.69 ± 3.63) ％ and (98.56± 0.48) ％,respectively.The radiochemical purity was more than 85％ after incubating in phosphate-buffered solution at room temperature for 72 h.(2) At 60,120,180 and 240 min post-injection,the binding ratios of 131I-anti-NRP-2-mAb in A549 cells were (3.95±0.18)％,(5.19±0.65) ％,(6.60± 0.36) ％ and (5.58± 0.63) ％,respectively.When excessive anti-NRP-2-mAb were added,the binding ratios were reduced to (0.94±0.31)％,(1.12±0.17)％,(1.24±0.25)％ and (1.04±0.18) ％,respectively,which were significantly lower than those of non-inhibited group (t values:9.89-19.66,all P＜0.05).131I-anti-NRP-2-mAb bound to NRP-2 with high affinity half maximal inhibitory concentration (IC50 =(410.8±1.2) nmol/L).(3) Biodistribution study demonstrated that the T/M and T/B ratios increased with the time extension and were 3.83±0.18 and 1.10±0.20,respectively,at 72 h post-injection.(4) Gamma imaging studies revealed that 131I-anti-NRP-2-mAb could clearly identify A549 tumors 6 h post-injection,especially at 48 h post-injection.Tumors were not observed clearly in competitive inhibition control group.Conclusion 131I-anti-NRP-2-mAb has been successfully prepared,and it could target to NRP-2 specifically.
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Objective To evaluate the efficacy and safety of 13-cis retinoid acid (13-CRA) and all trans retinoid acid (ATAR) redifferentiation therapy in patients with poorly differentiated thyroid cancer. Methods A single-center, randomized, double-blind, parallel controlled clinical trial was preformed. All patients were randomized into three groups. 78 cases were enrolled in each group. The patients were treated by 13-CRA in A group, by ATRA in B group, and by placebo in control group. The induced effects of retinoid acid (RA) and 131I treatment efficacies were defined as primary outcome of efficacy. Results After RA induction therapy, the effective rates in A, B, and control groups were 59.72%, 52.86% and 7.69%, respectively, with statistically significant difference among 3 groups (P<0.05). Compared with control group, A and B groups revealed significant induced efficacies (P<0.017), but there was no significant difference between A group and B group. After 131I treatment, the effective rates in A, B, and control group were 70.83%, 64.29%, and 28.21% respectively, with statistically significant difference (P<0.05). Compared with control group, the effective rates of 131I treatment in A and B groups were significantly raised (P<0.017), but there was no significant difference between A group and B group. The damage of skins and mucous membranes such as desquamation, dry skin, dry lips, dry eyes, etc occurred mostly in A group. The symptoms of nervous system such as headache, dizziness, etc occurred mostly in B group. Conclusions The induced differentiation of 13-CRA or ATRA is an effective method for the treatment of poorly differentiated thyroid carcinoma.
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Objective To synthesize 131I labeled anti-neuropilin-1 monoclonal antibody A6 (131IA6) and evaluate its biodistribution and imaging in malignant glioma xenografts.Methods (1) A6 was labeled with 131I by Iodogen method under the optimum labeling conditions,then the labeling efficiency,radiochemical purity and stability were measured in vitro.(2) In vitro bioactivity,cellular uptake and receptor affinity of 131I-A6 with U87MG cells were measured.(3) The nude mice bearing human U87MG cells were randomly divided into 5 groups with 5 in each group.The nude mice were sacrificed by cervical dislocation and dissected at 24,48,72,96,and 120 h,respectively,after intravenous injection of 1.2 MBq 131I-A6.The biodistribution of the agent was measured as ％ID/g,and the ratios of tumor/blood (T/B) and tumor/muscle (T/M) were calculated.(4) SPECT/CT imaging was performed in 6 mice including 3 in the competitive inhibition control group at 24,48,72,96,and 120 h post injection.Two-sample t test was used for data analysis.Results (1) The labeling yield of 131I-A6 was (95.46±3.34)％,and the radiochemical purity was more than 95％.At 96 h of incubation in PBS,the radiochemical purity was more than 85％.(2)131I-A6 had rapid accumulation in U87MG cells and reached the peak of (15.80±1.30)％ at 1 h.When the probe was incubated with large excesses of non-radioactive A6,the uptake level of 131I-A6 in U87MG cells was significantly inhibited (t=2.862,P＜0.05).Kd of 131I-A6 binding to NRP-1 was (1.67±0.14) nmol/L in U87MG cells.(3) Biodistribution study showed that the uptake in blood,liver and tumor was (8.00±1.42),(7.68±1.56) and (6.00±1.24) ％ID/g at 24 h,respectively.The uptake in muscle,brain and bone was lower.The T/B and T/M were 0.78±0.10 and 3.20±0.30 at 24 h,and they reached the highest level of 1.87±0.50 and 7.13±0.24 at 120 h.(4) The SPECT imaging showed that the tumors could be visualized at 24 h and delineated more clearly at 120 h post injection of 131I-A6.Conclusions 131I-A6 can be easily synthesized by Iodogen method with high radiochemical purity.The specific tumor uptake of 131I-A6,which correlates with NRP-1 expression in gliomas,suggests that it may be a new promising tumor targeting radiotracer.
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Objective To study the feasibility of a novel probe 99Tcm-HYNIC-2(poly-(ethylene glycol),PEG) 4-Dimer (Dimer:E-[c (RGDfK) 2]) as a potential imaging agent for integrin αv β3 positive tumors,and also to observe the influence of an angiogenesis inhibitor,endostar,on the biodistribution and tumor uptake of the tracer in tumor bearing nude mice.Methods The expression of integrin αv β3 in human glioma cells U87MG was determined with immunofluorescence staining before and after treatment with endostar.99Tcm-HYNIC-2PEG4-Dimer was prepared and administered in U87MG tumor bearing mice in 6 h after either administration of endostar (200 μl) or saline (control group) and then biodistribution study was performed.Other 16 mice were divided into endostar treated group (20 mg/kg) and control group (saline) and then gamma imaging was performed in the two groups.Statistical significance of differences between the two groups was assessed using two-sample t test.Results Radiochemical purity of 99Tcm-HYNIC-2PEG4-Dimer was exceeded 95％.The expression of integrin αvβ3 in U87MG cell was high and gradually decreased after treatment with endostar.There was a negative dose-effect relationship between the dose of endostar and the expression of integrin αvβ3 with the peak effect at the dose of 400 μg/ml.The distribution study in vivo showed that the tracer uptake of U87MG tumors was high,but it decreased after injection of endostar.At 90 min,the ％ID/g of endostar and control groups were 1.50±0.08 and 6.27±0.33,respectively (t =40.23,P＜0.05).The average T/NT ratios of 99Tcm-HYNIC-2PEG4-Dimer uptake in the endostar and control groups were 1.02±0.11 and 2.58±0.36,respectively (t =10.25,P＜0.05).The integrin αv β3 positive expression ratios of tumor in endostar and control groups were (33.1 ±2.7) ％ and (81.5±3.2) ％,respectively (t =32.60,P＜0.05).Conclusions The novel probe 99Tcm-HYNIC-2PEG4-Dimer may be a promising radiotracer for integrin αvβ3-positive tumor imaging.It may be used for monitoring the therapeutic effect of endostar and may be potentially used for screening the candidates of anti-angiogenesis therapy.